[ male announcer ] barack obama: failing to stop cheating. failing american workers. i'm mitt romney and i approve this message. >>> tonight on "world news," under fire. the president and secretary clinton facing tough questions today about the death of the u.s. ambassador and three other americans in libya. could they have been protected from the deadly attack? >>> runway rumble. a fight between two flight attendants broadcast on the passenger intercom. it delays an american airlines jet for hours. >>> sky high. the woman with a fear of heights trapped like this for four hours, 300 feet up. how did her husband come to the rescue? >>> and, robin's journey. a big day for our robin roberts. as she gets her bone marrow transplant and sends a message from a room filled with prayer. >>> good evening. we begin with the president, sending off heated questions tonight about the death of the u.s. ambassador chris stevens and three other americans who served in libya. both the president and the secretary of state, hillary clinton, were pressed to answer whether this could have